Nuclear Protection

Present Model RXG and R G-2 Beckmans are being replaced with nev units because of obsolesence and maintenance difficulties. The combination of these inits and the level trip from the Intermediate Range (Nuclear) Monitoring System will provide adequate high level nuclear protection. The octant monitoring concept is dropped from further consideration at this time. 

This review will not discuss issues or technologies covered within other chapters, such as ballistic, camouflage, chemical or nuclear protection however, their effect on the PDS for extremities protection will be acknowledged. The generic issues within extremities PPE will be discussed, with specific issues for... 

The Nuclear Protection and Safety Institute of the Commissariat a I Energie Atomique (CEA) is conducting a new important experimental program at the Valduc Criticality Laboratory in the field of criticality accident studies, both to provide consistent data for safety analysis and to improve its ability for facing a possible accidental situation. 

A nuclear protection system failure is covered by an independently designed secondary protection system, manual shutdown and post incident control measures. 

CEA, NUCLEAR PROTECTION AND SAFETY INSTTIUTE CADARACHE NUCLEAR CENTRE, FRANCE... 

The paper presents the results from systematic comparisons of contrast and resolution obtained with different types of radiation sources on steel thicknesses from 5 to 40 mm. These results have been taken into account with the definitions of the European standard for radiographic inspection of weldments (EN 1435) that is approved since 1997. Conclusions from practical investigations on pipe line sites, in petrochcemical plants and in nuclear power stations will be discussed as well. Furthermore, the presentation will stipulate a variety of advantages obtained from the new source in terras of coUimation and radiation protection. 

Fypass Flow Effects. There are several bypass flows, particularly on the sheUside of a heat exchanger, and these include a bypass flow between the tube bundle and the shell, bypass flow between the baffle plate and the shell, and bypass flow between the shell and the bundle outer shroud. Some high temperature nuclear heat exchangers have shrouds inside the shell to protect the shell from thermal transient effects. The effect of bypass flow is the degradation of the exchanger thermal performance. Therefore additional heat-transfer surface area must be provided to compensate for this performance degradation. 

Lead-loaded plastics containing up to 90 wt % lead are used in x-ray protection as aprons and temporary shields in medical and industrial appHcations. Leaded glass is used to attenuate radiation where viewing the ongoing process is requited. Steel-jacketed containers fihed with lead or special lead containers are used to transfer, ship, and store fuel rods, radioactive sources, and nuclear waste. Lead is generahy used where space is limited. 

Radiation dose limits at a disposal site boundary are specified by the NRC as 25 x 10 Sv/yr (25 mrem/yr), a small fraction of the average radiation exposure of a person in the United States of 360 x 10 /Sv/yr (360 mrem/yr). Protection against nuclear radiation is fully described elsewhere... 

The accident at the Three Mile Island (TMI) plant in Pennsylvania in 1979 led to many safety and environmental improvements (4—6). No harm from radiation resulted to TMI workers, to the pubHc, or to the environment (7,8), although the accident caused the loss of a 2 x 10 investment. The accident at the Chernobyl plant in the Ukraine in 1986, on the other hand, caused the deaths of 31 workers from high doses of radiation, increased the chance of cancer later in life for thousands of people, and led to radioactive contamination of large areas. This latter accident was unique to Soviet-sponsored nuclear power. The Soviet-designed Chemobyl-type reactors did not have the intrinsic protection against a mnaway power excursion that is requited in the test of the world, not was there a containment building (9—11). 

Eig. 1. The relation between physical barriers and levels of protection in defense-in-depth design of a nuclear faciUty (12). Courtesy of IAEA. 

Code of Federal Regulations, Tide 40, Protection of Environment, Part 190, Environmental Radiation Protection Standards for Nuclear Power Operations, Washington, D.C., 1976. 

The principal ha2ards of plutonium ate those posed by its radioactivity, nuclear critical potential, and chemical reactivity ia the metallic state. Pu is primarily an a-emitter. Thus, protection of a worker from its radiation is simple and usually no shielding is requited unless very large (kilogram) quantities are handled or unless other isotopes are present. 

R. T. Keimedy and M. B. Krat2er, Protection and Management of Plutonium, American Nuclear Society, LaGrange Park, HI., 1995. 

Protection of the environment from uncontroHed radioactive release is also a consideration in the use of radiotracers. The quantity and concentration of radionucHdes that may be discharged into sewer systems is limited by regulations of the Nuclear Regulatory Commission (NRC). 

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